The present invention relates to a scroll machine and, particularly, an improvement of such scroll machine utilizing a principle of a scroll compressor of a rotating driving scroll and a rotating driven scroll.
The principle of the scroll compressor is well known as a kind of volume compression type in which compression effect is obtained by a combination of a pair of convolute protrusions. One of the convolute protrusions is usually stationary and the other is rotated to compress fluid. On the other hand, the operational principle of the so-called full rotation type scroll compressor in which both scrolls are rotated about their rotation centers is also well known as disclosed in, for example, U.S. Pat. No. 2,475,247.
FIG. 5 is an illustration showing the principle of the full rotation type scroll compressor, in which a driving scroll 1 is rotated about a center axis O.sub.1 by a driving source such as electric motor, engine or turbine. A driven scroll 2 is also rotated about its center axis O.sub.2 in synchronism with the driving scroll 1. A compression chamber 3 is moved inwardly during rotations of these scrolls to reduce its volume to thereby increase a pressure of gas therein, a resultant high pressure gas being discharged from a discharge port 2c.
In a state (a) of the scroll compressor shown in FIG. 5 in which a rotation angle is 0.degree., gas is introduced into the compression chamber 3. With a further rotation from 0.degree. to 360.degree., the compression chamber 3 moves toward the center gradually as shown by states (b) to (d) to reduce its volume. During this movement, radial seal portions S between convolute protrusions 1a and 2a of the scrolls 1 and 2 are stationary and arranged along a radial straight line.
As is well known, since a gravity center of the convolute protrusion of each scroll is around an end of its convolution, an imbalance is compensated by forming a recess in a circular plate portion as shown in Japanese Utility Model application Laid-Open No. 126095/1986.
The formation of such recess requires a relatively complicated milling, causing a scroll machine to be expensive.